OpenMD 3.1
Molecular Dynamics in the Open
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Constants.hpp
1/*
2 * Copyright (c) 2004-present, The University of Notre Dame. All rights
3 * reserved.
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9 * this list of conditions and the following disclaimer.
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17 * this software without specific prior written permission.
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28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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30 *
31 * SUPPORT OPEN SCIENCE! If you use OpenMD or its source code in your
32 * research, please cite the appropriate papers when you publish your
33 * work. Good starting points are:
34 *
35 * [1] Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).
36 * [2] Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).
37 * [3] Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).
38 * [4] Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
39 * [5] Kuang & Gezelter, Mol. Phys., 110, 691-701 (2012).
40 * [6] Lamichhane, Gezelter & Newman, J. Chem. Phys. 141, 134109 (2014).
41 * [7] Lamichhane, Newman & Gezelter, J. Chem. Phys. 141, 134110 (2014).
42 * [8] Bhattarai, Newman & Gezelter, Phys. Rev. B 99, 094106 (2019).
43 */
44
45#ifndef UTILS_CONSTANTS_HPP
46#define UTILS_CONSTANTS_HPP
47
48#include <config.h>
49
50#ifdef _MSC_VER
51#include <math.h>
52#else
53#include <cmath>
54#endif
55
56namespace OpenMD::Constants {
57
58 static constexpr RealType PI = M_PI;
59 static constexpr RealType TWO_PI = 2.0 * PI;
60
61 // Internal units in OpenMD:
62 // distance = Angstroms (1.0e-10 m)
63 // time = fs (1.0e-15 s)
64 // mass = amu
65 // charge = electron charge (1.602176634e-19 Coulombs)
66 // energy = kcal/mol
67 // temperature = K
68 // velocity = Angstroms / fs
69 // force = kcal/mol / Angstroms
70
71 inline constexpr RealType kb =
72 1.9872156E-3; //!< boltzman's constant in kcal/(mol K)
73 inline constexpr RealType kB =
74 8.31451e-7; //!< boltzmann constant amu*Ang^2*fs^-2/K
75 inline constexpr RealType c =
76 299792458. * 1e-5; //! speed of light in Ang fs^-1
77 inline constexpr RealType epsilon0 =
78 2.396451e-4; //! vacuum permittivity in e^2 Ang^-1 (kcal/mol)^-1
79 inline constexpr RealType mu0 =
80 1.25663706212e-6; //! vacuum permeability in N Amp^-2
81
82 inline constexpr RealType energyConvert =
83 4.184E-4; //!< convert kcal/mol -> (amu A^2)/fs^2
84 inline constexpr RealType rotationalEnergyConvert = energyConvert * TWO_PI;
85
86 inline constexpr RealType pressureConvert =
87 1.63882576e8; //!< converts amu*fs^-2*Ang^-1 -> atm
88 inline constexpr RealType elasticConvert =
89 1.66053386e4; //!< converts amu*fs^-2*Ang^-1 -> GPa
90 inline constexpr RealType energyElasticConvert =
91 6.947695345; //!< converts kcal*mol^-1*Ang^-3 -> GPa
92
93 //! \name chargeFieldConvert Converts electron-volts to kcal/mol
94 inline constexpr RealType chargeFieldConvert = 23.0609;
95 //! \name dipoleFieldConvert Converts Debye*Volts/Angstroms to kcal/mol
96 inline constexpr RealType dipoleFieldConvert = 4.8018969509;
97 //! \name dipoleConvert Converts Debye to electron Angstroms
98 inline constexpr RealType dipoleConvert = 0.2081943;
99
100 //!\name magneticFieldConvert Converts Tesla to Volts fs/Ang^2
101 inline constexpr RealType magneticFieldConvert = 1.0e-5;
102
103 /**
104 * surfaceTensionConvert
105 * multiplies standard input file units of
106 * surfaceTension (Newton / meter)
107 * returns values of
108 * kcal mol^-1 Angstrom^-2
109 */
110 inline constexpr RealType surfaceTensionConvert =
111 1.439326479; //!< converts N/m to kcal/mol*Ang^-2
112
113 /**
114 * viscoConvert
115 * used for products of:
116 * viscosity (Poise) * distance (Angstroms) * velocity (Angstrom / fs)
117 * returns values of:
118 * force in (kcal mol^-1 Angstrom^-1)
119 */
120 inline constexpr RealType viscoConvert = 1.439326479e4;
121
122 /**
123 * densityConvert
124 * used for converting amu / Angstroms^3 into g / cm^3
125 */
126 inline constexpr RealType densityConvert = 1.66053886;
127
128 /**
129 * thermalConductivityConvert
130 * multiplies standard input file units of
131 * themalConductivity (watts meter^-1 Kelvin^-1)
132 * returns values of:
133 * kcal mol^-1 Angstrom^-1 fs^-1 Kelvin^-1
134 */
135 inline constexpr RealType thermalConductivityConvert = 1.439326479e-5;
136
137 /**
138 * currentConvert
139 * multiplies standard input file units of
140 * electricalCurrent (Amperes)
141 * returns values of:
142 * electrons fs^-1
143 */
144 inline constexpr RealType currentConvert = 6241.573027317;
145
146 /**
147 * currentDensityConvert
148 * multiplies standard input file units of
149 * currentDensity (Amperes m^-2)
150 * returns values of:
151 * electrons fs^-1 Angstrom^-2
152 */
153 inline constexpr RealType currentDensityConvert = 6.241573027317e-17;
154
155 /**
156 * chargeDensityConvert
157 * multiplies standard input file units of
158 * chargeDensity (Coulombs m^-2)
159 * returns values of:
160 * electrons Angstrom^-2
161 */
162 inline constexpr RealType chargeDensityConvert = 6.241573027317e-2;
163
164 /**
165 * concentrationConvert
166 * multiplies standard number density units (Angstrom^-3)
167 * returns values of molarity (1 M = 1 mole / Liter)
168 */
169 inline constexpr RealType concentrationConvert = 1660.5390404272;
170
171 /**
172 * Atomic Units are used in the Slater overlap code, and we need
173 * to get distances back and forth to angstroms and energies back
174 * and forth to kcal / mol
175 */
176 inline constexpr RealType angstromToBohr = 1.88972612;
177 inline constexpr RealType bohrToAngstrom = 0.52917721092;
178 inline constexpr RealType hartreeToKcal = 627.509469;
179} // namespace OpenMD::Constants
180
181#endif